If you’re familiar or well-acquainted with what’s going on in psychiatry, you’ve probably heard about the next promising help for severely depressed patients. Some studies and patients will attest to how quickly ketamine takes into affect while antidepressants might take up to a few weeks. Surprisingly, patients with treatment-resistant depression have also reported that ketamine is effective for themselves.
With new research, we may be able to unveil how ketamine may actually help depression. With neurons in the brain’s mesolimbic system promoting reward-seeking behavior, we are prone to process information about our actions that eventually result in pleasurable outcomes. However, neurons in the lateral habenula (LHb) process the unpleasant information of our actions thus suppressing the reward-seeking behavior. From this asymmetric system between our neurons in the mesolimbic system and the lateral habenula(LHb), it suggests that this may contribute to the mood disorders like depression. Yet, with the help of ketamine, the activity within the lateral habenula (LHb) is blocked which helps in the regions that are depression prone.
Studies suggest that the LHb acts as a ‘dark twin’ or ‘disappointment circuit’ to the reward centers of the brain by processing unexpected unpleasant events. Think of it like this; you’re used to a certain pattern that results in reward but when the pattern is broken with no reward, your brain processes this discrepancy. If the LHb is overactive, it could trigger anhedonia which means the inability to feel pleasure. After several experiments and studies, researchers began to hypothesize that the LHb connects to part of the limbic system. The limbic system processes emotions. The LHb also connects to the reward centers that signal using chemical messengers. The LHb inhibits activity in these regions therefore making burst firing more effective when stopping the production of reward signals.
While ketamine has been a licensed anesthetic since the 1970s, it wasn’t until almost 20 years ago that researchers began to study the antidepressant properties ketamine held. Other antidepressants may directly influence chemical messengers like serotonin. However, ketamine works through the interactions between other chemicals like glutamate. Glutamate is commonly associated with mood rather than brain plasticity. There are suggestions that ketamine helps relieve depression through the growth of new neural connections.
These new findings shed some light on a drug that would otherwise be associated as a club drug. Once studies are done in order to figure out how ketamine is able to act quickly, there will be more potential insight on depression as well as developing the next generation of ketamine based treatments. Needless to say, researchers are still studying ketamine as a means of a way out of depression alongside the safety and optimum doses needed. With the studies of ketamine providing positive results, it seems that there is something to look forward to for patients soon.